CN104535199A - Terahertz wave frequency coherent measurement method - Google Patents
Terahertz wave frequency coherent measurement method Download PDFInfo
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- CN104535199A CN104535199A CN201510012835.3A CN201510012835A CN104535199A CN 104535199 A CN104535199 A CN 104535199A CN 201510012835 A CN201510012835 A CN 201510012835A CN 104535199 A CN104535199 A CN 104535199A
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Abstract
The invention discloses a terahertz wave frequency coherent measurement method, belongs to the technical field of terahertz detection and relates to terahertz wave frequency detection and calculation. The method is similar to optical coherent measurement frequency design. One path of terahertz waves are converted into two paths of terahertz waves through a corresponding optical element, then, the optical path of one path of terahertz waves to be detected is changed through a mobile device, the path of terahertz waves and the other path of terahertz waves are enabled to generate a periodical interference phenomenon, a pyroelectric detector of power measuring equipment of a terahertz waveband is used for detecting output power, the amplitude of the output power detected by the pyroelectric detector changes along with coherent changes, and terahertz wave frequency to be detected is calculated through the changed information and the displacement distance of the mobile device. The measurement element involved in the method is simple in structure, a light path can be established easily, operation is convenient and measurement efficiency and measurement accuracy are very high.
Description
Technical field
The invention belongs to Terahertz detection technique field, relate to detection and the calculating of THz wave frequency, specifically a kind of a kind of measuring method measuring THz wave band frequency.
Background technology
THz wave is frequency 0.1 ~ 10THz (1THz=10
12hz) electromagnetic wave in scope, the wavelength coverage of its correspondence is 3mm ~ 30 μm, is positioned between millimeter wave (submillimeter wave) and infrared waves.The corresponding energy range of Terahertz photon is 0.414 ~ 41.4meV, matches with the low-frequency vibration of molecule and material and rotational energy scope.These determine the specific position of THz wave in electromagnetic spectrum and in propagation, scattering, reflection, absorb, to penetrate etc. in the features and application significantly different from millimeter wave, infrared ray.And Terahertz Technology also provides very large free space by for people to the sign of material and manipulation.Such as, terahertz emission has good space-time coherence, and this is realize quantum coherent and Quantum control provides new means.And the ability in high resolving power continuous coverage and time domain measurement two also greatly extends the effect of tera-hertz spectra in astrophysics and atmospheric science.
Terahertz wave band is between microwave region and light-wave band, and this singularity brings a lot of difficulty to its signal measurement, and especially frequency measurement is more difficult.THz wave is too high relative to traditional microwave signal frequency, and frequency spectrograph or oscillograph cannot be used directly to measure; And it is too low relative to lightwave signal frequency, the method for interference cannot be adopted to carry out survey frequency.What the frequency measurement of current Terahertz long-wave band was generally applied is process of heterodyning, it is by local oscillated signal difference frequency suitable with frequency for measured signal, tested Terahertz wave frequency is obtained by analyzing the intermediate-freuqncy signal exported, but extrapolation needs the local vibration source providing a frequency suitable, this local vibration source easily realizes in Terahertz low-frequency range, to be difficult to realize at high band, moreover provide a wide band local vibration source to be quite difficult, this will considerably increase the cost of Terahertz frequency measurement.At present owing to almost not having wide band Terahertz power source on the market, this just greatly constrains the development of Terahertz frequency measurement technology.Because terahertz wave band is between microwave and light wave, so the measurement of THz wave frequency can copy the principle of optical coherence to realize frequency measurement.
Summary of the invention
The object of the invention is to use that a kind of structure of simple element design is simple, easy to operate, efficiency is higher, the significant Terahertz frequency measurement method of performance.This design mainly comprises terahertz signal source to be measured, Terahertz convergent mirror, Terahertz completely reflecting mirror, stepper motor, pyroelectric detector and data acquisition process equipment.
The present invention is a kind of method of coherent measurement THz wave frequency, and first the method changes Terahertz incident wave into two bundles parallel THz wave, and change wherein a branch of Terahertz wave propagation distance, the final direction of propagation is consistent with the direction of propagation originally; Again the parallel THz wave of two bundles is converged to a place by convergent mirror, then detect the energy of this place's THz wave with pyroelectric detector, and real time record; By changing wherein a branch of Terahertz wave propagation distance, thus make two bundle ripples of arrival pyroelectric detector that relevant effect occur; The energy that pyroelectric detector detects changes along with the distance of wherein a branch of THz wave and changes, the twice of the knots modification of the distance of wherein a branch of THz wave corresponding between the adjacent energy maximal value thus having pyroelectric detector to detect is the wavelength of this THz wave, and then calculates its frequency.
Further, first Terahertz incident wave is changed into two bundles parallel THz wave, wherein a branch of THz wave is with the reflection of the incident angle of 45 ° respectively through completely reflecting mirror a, b, c, d, finally return on its initial travel path, completely reflecting mirror b, c are fixed on same mirror holder, are realized the change of this bundle Terahertz wave propagation distance by this mirror holder mobile.
The present invention's design is a kind of method measuring THz wave frequency, the method is similar to the design of optical coherence survey frequency, a road THz wave is changed into two-way by corresponding optical element, then the light path of the THz wave to be measured on a wherein road is changed by mobile device, make it the interference producing the cycle with another road, the power-measuring device pyroelectric detector of recycling terahertz wave band detects output power, the change that the output power amplitude that pyroelectric detector detects is concerned with has corresponding change, Terahertz wave frequency to be measured is calculated by the information of this change and the displacement of mobile device.The measuring sensor structure related in the present invention is simple, and light path is easily built, easy to operate, measure efficiency and measuring accuracy very high.
Accompanying drawing explanation
Fig. 1 is principle schematic of the present invention.
Fig. 2 is the data plot that signal acquisition process device described point is drawn.
In figure: 1. terahertz emission source, 2. Terahertz incident wave, 3. Terahertz convergent mirror a, 4. Terahertz is concerned with incident wave, 5. completely reflecting mirror a, 6. completely reflecting mirror b, 7. optical total-reflection mirror support, 8. completely reflecting mirror c, 9. one dimension stepper motor, 10. Terahertz coherent wave, 11. completely reflecting mirror d, 12. Terahertzs are concerned with outgoing wave, 13. Terahertz incident wave control groups, 14. Terahertz convergent mirror b, 15. Terahertz output waves, 16. pyroelectric detectors, 17. signal acquisition process devices.
Embodiment
Below in conjunction with Figure of description and description of reference numerals, the specific embodiment of the present invention is further elaborated.
The effect introduction of each element:
1. terahertz emission source, terahertz signal source to be measured, is placed on a focus place of 3 Terahertz convergent mirror a;
2. Terahertz incident wave, terahertz signal source to be measured projects the part of 3 Terahertz convergent mirror a;
3. Terahertz convergent mirror a, for dispersing 2 Terahertz incident waves, obtains two-way parallel wave;
4. Terahertz is concerned with incident wave, for generation of a branch of parallel wave of Terahertz coherent wave;
5. completely reflecting mirror a, for changing the light path of 2 Terahertz incident waves, to form Terahertz coherent wave;
6. completely reflecting mirror b, for changing the light path of 2 Terahertz incident waves, to form Terahertz coherent wave;
7. optical total-reflection mirror support, is arranged on 9 one dimension stepper motors, for fixed support 5 completely reflecting mirror a and 6 completely reflecting mirror b;
8. completely reflecting mirror c, for changing the light path of 10 Terahertz coherent waves, to be concerned with outgoing wave to form 12 Terahertzs;
9. one dimension stepper motor, fixes 7 optical total-reflection mirror supports, accurately can control the movement of its horizontal direction, to be concerned with the light path of incident wave to change 4 Terahertzs;
10. Terahertz coherent wave, this wave frequency, amplitude are identical with 13 Terahertz incident wave control groups, and phase place is different with 13 Terahertz incident wave control groups, are the coherent waves of 13 Terahertz incident wave control groups;
11. completely reflecting mirror d, for changing the light path of 10 Terahertz coherent waves, to be concerned with outgoing wave to form 12 Terahertzs;
12. Terahertzs are concerned with outgoing wave, this wave frequency, amplitude are identical with 13 Terahertz incident wave control groups, phase place is different with 13 Terahertz incident wave control groups, and the change of its phase place is caused by the movement of 9 one dimension stepper motor horizontal directions, is the coherent wave of 13 Terahertz incident wave control groups;
13. Terahertz incident wave control groups, another bundle parallel wave that 2 Terahertz incident waves are formed through 3 Terahertz convergent mirror a beam splitting;
14. Terahertz convergent mirror b, to be concerned with outgoing wave and 13 Terahertz incident wave control groups for assembling 12 Terahertzs;
15. Terahertz output waves, terahertz wave signal to be measured, wherein includes 12 different Terahertzs of phase information and to be concerned with outgoing wave and 13 Terahertz incident wave control groups;
16. pyroelectric detectors, for detecting the output power of 15 Terahertz output waves, convert terahertz wave signal to electric signal so that data acquisition process;
17 signal acquisition process devices, the terahertz wave signal received by 16 pyroelectric detectors carries out data acquisition and data processing, and obtains the incident wave frequency of 2 Terahertzs according to analytical calculation.
Each element is built light path according to the design shown in Fig. 1.Terahertz emission source is placed in a focus of Terahertz convergent mirror a, it is for generation of THz wave to be measured, a part wherein becomes Terahertz incident wave and enters Terahertz convergent mirror a, through the beam splitting effect of Terahertz convergent mirror a, Terahertz incident wave is resolved into two-way parallel wave, wherein a road is that Terahertz is concerned with incident wave, another road is Terahertz incident wave control group, the Terahertz incident wave that is concerned with forms Terahertz coherent wave after completely reflecting mirror a and completely reflecting mirror b reflect, Terahertz coherent wave forms Terahertz and to be concerned with outgoing wave after completely reflecting mirror c and completely reflecting mirror d reflect, be concerned with outgoing wave and Terahertz incident wave control group of Terahertz forms Terahertz output wave after Terahertz convergent mirror b assembles, place a pyroelectric detector receive terahertz wave signal at the focus place of Terahertz convergent mirror b opposite side and be converted into electric signal, connect a signal acquisition process device after pyroelectric detector and data acquisition and data processing work are done to the terahertz signal collected.
During formal measurement THz wave frequency, first by one dimension stepper motor as initial bit reset, now pyroelectric detector can detect a performance number, the performance number that the position data of signal acquisition process device record one dimension stepper motor and pyroelectric detector detect, one dimension stepper motor is chosen suitable stepping accuracy and is carried out unidirectionally repeatedly moving, one dimension stepper motor often moves once, the performance number that signal acquisition process device detects with regard to the position data and pyroelectric detector recording one group of one dimension stepper motor, the repeatedly mobile lower signal acquisition process device of one dimension stepper motor can obtain a two-dimensional array, in this two-dimensional array, the position data of one dimension stepper motor is as horizontal ordinate, the performance number that pyroelectric detector detects is drawn as ordinate, just obtain discrete sine curve as shown in Figure 2, and mark first time occur that the position x2 of peak value appears in the position x1 and n-th of peak value.Had these data just can go out the frequency values in terahertz emission source according to formulae discovery, its computing formula is
In fact, what one dimension stepper motor mobile changed is the optical path difference that Terahertz is concerned with between outgoing wave and Terahertz incident wave control group, and one dimension stepper motor often moves the distance of Δ x, and optical path difference just changes 2 Δ x, according to optical coherence principle
and the relation f=c/ λ of frequency and wavelength can draw above-mentioned frequency computation part formula
The present invention applies the principle of optical coherence for the method measuring THz wave frequency, the each element adopted is finished product comparatively conventional on the market, advantage of lower cost, and building of light path realizes than being easier to, the operating process of actual measurement is simple, measure efficiency and accuracy all higher.
More than show and describe ultimate principle of the present invention and principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; what describe in above-described embodiment and instructions just illustrates principle of the present invention; under the premise without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.Application claims protection domain is defined by appending claims and equivalent thereof.
Claims (2)
1. a method for coherent measurement THz wave frequency, first the method changes Terahertz incident wave into two bundles parallel THz wave, and change wherein a branch of Terahertz wave propagation distance, the final direction of propagation is consistent with the direction of propagation originally; Again the parallel THz wave of two bundles is converged to a place by convergent mirror, then detect the energy of this place's THz wave with pyroelectric detector, and real time record; By changing wherein a branch of Terahertz wave propagation distance, thus make two bundle ripples of arrival pyroelectric detector that relevant effect occur; The energy that pyroelectric detector detects changes along with the distance of wherein a branch of THz wave and changes, the twice of the knots modification of the distance of wherein a branch of THz wave corresponding between the adjacent energy maximal value thus having pyroelectric detector to detect is the wavelength of this THz wave, and then calculates its frequency.
2. the method for a kind of coherent measurement THz wave frequency as claimed in claim 1, it is characterized in that first changing Terahertz incident wave into two bundles parallel THz wave, wherein a branch of THz wave is with the reflection of the incident angle of 45 ° respectively through completely reflecting mirror a, b, c, d, finally return on its initial travel path, completely reflecting mirror b, c are fixed on same mirror holder, are realized the change of this bundle Terahertz wave propagation distance by this mirror holder mobile.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111220282A (en) * | 2020-01-10 | 2020-06-02 | 赫立科技（成都）有限公司 | Terahertz frequency measurement structure based on waveguide resonant cavity and method thereof |
| CN113321930A (en) * | 2021-05-31 | 2021-08-31 | 四川大学 | Method for 3D printing of terahertz modulation material with gradient modulation amplitude based on laser sintering |
| TWI786094B (en) * | 2017-03-14 | 2022-12-11 | 柏林工業大學 | Method and apparatus for carrying out a time-resolved interferometric measurement |
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| CN102213682A (en) * | 2011-04-18 | 2011-10-12 | 中国计量学院 | Method for measuring transmission of interference-insensitive terahertz wave |
| CN202177460U (en) * | 2011-07-14 | 2012-03-28 | 华中科技大学 | Wavelength meter of terahertz light |
| CN103635775A (en) * | 2011-06-27 | 2014-03-12 | 赫克斯冈技术中心 | Interferometric distance measuring method for measuring surfaces, and such a measuring arrangement |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101290248A (en) * | 2007-04-18 | 2008-10-22 | 中国科学院半导体研究所 | Single-mode infra-red wavemeter based on Mach-Zehnder Interferometer filtering principle |
| CN102213682A (en) * | 2011-04-18 | 2011-10-12 | 中国计量学院 | Method for measuring transmission of interference-insensitive terahertz wave |
| CN103635775A (en) * | 2011-06-27 | 2014-03-12 | 赫克斯冈技术中心 | Interferometric distance measuring method for measuring surfaces, and such a measuring arrangement |
| CN202177460U (en) * | 2011-07-14 | 2012-03-28 | 华中科技大学 | Wavelength meter of terahertz light |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI786094B (en) * | 2017-03-14 | 2022-12-11 | 柏林工業大學 | Method and apparatus for carrying out a time-resolved interferometric measurement |
| CN111220282A (en) * | 2020-01-10 | 2020-06-02 | 赫立科技（成都）有限公司 | Terahertz frequency measurement structure based on waveguide resonant cavity and method thereof |
| CN111220282B (en) * | 2020-01-10 | 2021-11-30 | 赫立科技（成都）有限公司 | Terahertz frequency measurement structure based on waveguide resonant cavity and method thereof |
| CN113321930A (en) * | 2021-05-31 | 2021-08-31 | 四川大学 | Method for 3D printing of terahertz modulation material with gradient modulation amplitude based on laser sintering |
| CN113321930B (en) * | 2021-05-31 | 2022-05-03 | 四川大学 | Method for 3D printing of terahertz modulation material with gradient modulation amplitude based on laser sintering |
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